Crack Cocaine

Cocaine is a powerful constrictor of blood vessels and a local
anaesthetic. It is also a potent psychostimulant.
The physical effects of cocaine on the user include excitement, alertness, tachycardia,
pupillary dilatation, raised body-temperature, hypertension, brochodilation, enhanced
glucose availability, and increased motor activity - all part of the "fight or
flight" syndrome.

Taking
cocaine also also gets you high. Its half-life in the plasma, however, is only
50 minutes; and the euphoria soon fades. Freebase/crack users desire more of the
drug far sooner than users of the hydrochloride salt.

The
rewarding properties of cocaine derive mainly from its effects on the neurotransmitter
dopamine. The dopamine system is involved in
the control of mood, motivation, cognition, locomotion, sexuality and endocrine
function. There are only some 30-40 thousand dopamine neurons in the brain, but
both the axons and dentrites of the dopamine neurons are unusually well arborised
- with as many as 100,000 synapses for each dopaminergic neuron. Their distinctive
morphology reflects dopamine's role in the "encephalisation of emotion".

Cocaine
induces elation primarily by blocking the dopamine
transporter. The blockade increases the availability of free dopamine in the
mesolimbic pleasure-centres of the brain. Degree of transporter occupancy is correlated
with the intensity of euphoria. Higher doses and faster routes of administration
create vivid memories and intense cravings. But the biological substrates
of pure pleasure remain elusive.
Investigation of the possible final common pathway of pleasure in the brain continues.
Endorphins and enkephalins activating receptors in the ventral
pallidum apparently play a role too, as does the orbitofrontal
cortex.

Recent research highlights
the role of the sigma1 receptors in cocaine-induced
euphoria. Co-administering a sigma1 agonist
makes taking cocaine even more enjoyable. Sigma1 agonists like igmesine
are also under investigation as potential antidepressants.
Conversely, taking a sigma1 receptor antagonist
makes cocaine use unrewarding.

Whatever
its mechanisms, and unlike most clinically-approved
mood-brighteners, cocaine is a pro-sexual drug. Taken before sex, it can induce
prolonged and intense orgasm. Cocaine-induced lovemaking, however, is not especially
warm or empathetic.